-- card: 74375 from stack: in
-- bmap block id: 74709
-- flags: 0000
-- background id: 2665
-- name: 


-- part 1 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=205 top=315 right=337 bottom=256
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: NEXT
----- HyperTalk script -----
on mouseUp
  go to next card
end mouseUp



-- part 2 (button)
-- low flags: 00
-- high flags: 8003
-- rect: left=149 top=314 right=337 bottom=199
-- title width / last selected line: 0
-- icon id / first selected line: 0 / 0
-- text alignment: 1
-- font id: 0
-- text size: 12
-- style flags: 0
-- line height: 16
-- part name: PREV.
----- HyperTalk script -----
on mouseUp
  go back
end mouseUp



-- part contents for background part 1
----- text -----
NONDISJUNCTION

-- part contents for background part 2
----- text -----
When nondisjunction occurs in a human ovary, the same chromosomal imbalance occurs. XO and XX/ individuals are seen in the human race. XO individuals are poorly developed females displaying a series of phenotypic traits known as Turner's syndrome. The XX/ individuals (XXY) are poorly developed males displaying a series of phenotypic traits known as Kleinfelter's syndrome. Whether a Turner's XO or a Kleinfelter's XXY, these individuals show poor sexual development and other phenotypic traits. From this, can you come up with a mechanism for sex determination in humans? Think about it, transcribe your comments and then scroll for your answer.
YOUR COMMENT:













In humans, sex is determined by a balance of metabolic forces that include, as in Drosophila the X to autosome ratio in addition to maleizing influences contained on the Y chromosome. Thus an XX/ individual has the normal X/ chromosome balance for males but in addition, the XX balance for females. Hence the failure to develop fully along a specific sexual line. The XO individual has the X to autosome ratio of males but lacking a functional Y chromosome, normal male development is impossible. For problems with nondisjunction among autosomes, flip to the next card.